Which is the correct sentence for synthesis?

There is nothing in the original pair of sentences to indicate which animal climbed the tree. They are a very poor choice.

contrex wrote:

There is nothing in the original pair of sentences to indicate which animal climbed the tree. They are a very poor choice.

Thanks, Contrex.

I have amended the sentences as follows. I hope they are OK now.

The monkey saw a tiger. The monkey climbed up a tree.
If the above sentences are joined, which of the following sentences is correct?

No sooner had the monkey seen a tiger than it climbed up a tree.

No sooner did the monkey see a tiger than it climbed up a tree.

Thanks.